This page shows the second method of the submenu work(Pro version only).
By default submenu drops down when you mouse hover the parent(level 1) menu item, but alternatively you can switch it by clicking only. It's good if you have lot's of submenu items in a few columns.
Try to mouse hover(as usual it should drop down) and try to click.
There's below just a simple live sheme of the element alignment... of course it's just to see, and it's wrong and will be corrected later